This patent application is co-pending with my eight other patent applications Ser. Nos. 798,058; 798,059; 798,060; 798,061; 798,062; 798,063; 798,065; 798,066 and having the same filing date of May 18, 1977; related to a high pressure air turbine-gear train system describing and claiming various aspects thereof.
This invention relates to a gear-train system and more particularly to a low-noise, high-power, lightweight and compact turbine-gear train system for driving an axial flow water pump for ejecting or launching torpedoes from submerged submarine tubes while generating the least amount of radiated noise, occupying the smallest volume and requiring the least maintenance.
During World War II, submarine fired torpedoes were primarily launched by blowing a charge of compressed air into the tube behind the weapon in the same way as one propels a pea from a peashooter. However, this generated a large air bubble in the water which not only made noise but visually identified the submarine firing position. Later on this adverse condition was circumvented and additional advantages realized by using a single piston, single stroke hydraulic pump to displace water which in turn displaced or launched the torpedo. Air was still used as the energy source, but only to drive the hydraulic piston which operated with ambient depth pressures on its inlet side. The air spent was discharged into the submarine and thereby no identifiable air bubble existed outside the submarine. Furthermore, the work required was lessened because the firing depth pressure was equalized on the fore and after ends of the firing tubes. However, the disadvantages of this system were that it was exceedingly noisy, required a lot of space for the mechanical hardware, and was very heavy thereby taxing the submarines useful load. Furthermore, the stresses in the structural systems were high. The noise generated of the system was further aggravated by the need to return the system to "battery" or initializing position.
Later on a system incorporating a turbine and a gear train to drive an axial flow pump, which pressurized the after end of the torpedo launched tube with seawater, was conceived and built to demonstrate the practicability of launching torpedoes using relatively lightweight systems. However, it did not include noise reduction considerations and did not satisfy the power requirements to meet the required ejection velocities which became higher because of increased submarine performance. Besides, the system was underpowered for the application, its planet carrier structure was torsionally flexible causing misalignments of planet gear axes relative to the sun and ring gear axes and resulting in adverse tooth loading and noise. In addition, the shaft stiffness between first and second stage gear clusters was not the same for all clusters causing an uneven distribution of load among the planet clusters which thereby aggravated the tooth stress. Furthermore, the ring gear design permitted distortions of pitch line under the influence of load and further contributed to uneven distribution and increased tooth stresses. Furthermore, the gear tooth size was too large to permit at least a two tooth contact ratio which thereby caused a less desirable load transfer transient at successive tooth engagements and contributed to noise. Besides, the relatively large teeth also limited the precision to which it could be manufactured which resulted in greater errors in action and larger dynamic loads. No attempt was made to reduce noise transmitted to support structures. It is thus desirable to have a turbine-gear train system which will be free of the above-identified defects.